Boiling and Burnout Phenomena under Transient Heat Input : 1st Report, Experiment

Abstract

In order to simulate the thermo-hydrodynamic conditions at reactor power excursions, a test piece was placed in a forced convective channel and heated with exponential power inputs. The boiling heat transfer and the burnout heat flux under the transient heat input were measured, and pressure and water temperature changes in the test section were recorded at the same time. Following experimental results were obtained ; (1) Transient boiling heat transfer characteristics at high heat flux stayed on the stationary nucleate boiling curve of each flow condition, or extrapolated line of the curves. (2) Transient burnout heat flux increased remarkably with decreasing heating-time-constant, when the flow rate was lower and the subcooling was higher. (3) transient burnout phenomena were expressed with the relation of (q_max-q_sBO)_T = constant at several flow conditions. This relation was derived from the stationary burnout mechanism of pool boiling.